1. Field of the Invention
Embodiments of the present invention generally relate to a system, device, and method for dithering to avoid gamma curve errors.
2. Description of the Related Art
Display devices are widely used in a variety of electronic systems to provide visual information to a user. For example, display devices may be used to provide a visual interface to an electronic system, such as a desktop computer. Advancements in display technologies have enabled display devices to be incorporated into an increasing number of applications, such as laptop computers, tablet computers, and mobile phones. In such applications, display devices are capable of providing high-resolution interfaces having high contrast ratios and relatively accurate color reproduction.
Display devices are capable of reproducing a wide range of color values within a given color space. For example, conventional displays using a red, green, and blue (RGB) sub-pixel arrangement typically represent each color channel using 8 bits per pixel, or 256 discrete levels per color channel per pixel. Thus, each RGB pixel can represent approximately 16.7 million discrete color values.
Prior to display, each color value is provided to a display processor, which performs digital-to-analog conversion (DAC) and outputs the appropriate analog values (e.g., voltages, currents, etc.) for each sub-pixel of the display. The proper analog value(s) needed to accurately reproduce a particular color value depends on various characteristics of the display. For example, in some liquid crystal display (LCD) technologies, the transmissivity of a liquid crystal increases with applied voltage, as shown in FIG. 1. Thus, in such LCD displays, to increase the brightness of a particular pixel or sub-pixel, the voltage applied to the liquid crystal must be increased.
In general, the analog values required to accurately reproduce each incoming color value—at a given gamma value—may be approximated using a piecewise linear approximation. For example, with reference to FIG. 1, the curve that maps incoming color values to the voltages required to accurately reproduce the color values may be approximated using a series of straight lines. However, due to various display characteristics (e.g., material properties, manufacturing variations, device temperature, device age, and the like), the curve that maps incoming color values to their corresponding analog values may include one or more perturbations or bumps that cannot accurately be approximated using a reasonable number of straight lines. Accordingly, approximating such perturbations using one or more straight lines may cause the display processor to output voltages that are too high or too low to accurately reproduce a particular color value, resulting in an image that is too bright or too dark and/or producing color bands at color values associated with the perturbations.
Therefore, there is a need in the art for a technique for avoiding pixel value conversion errors in a display device.